Blower wheel bracing



c. 1. PLACE 2,424,501

' BLOWER WHEEL BRACING July 22, 1947.

Filed May -7, 1945 FIG.4.

INVENTOR; CHARLES 1'.- PLACE rron/vs) Patented July 22, 1947 UNITED STATES PATENT OFFICE BLOWER WHEEL BRAGING Charles I. Place, New Milford, Cnn., assignor to The Torrington Manufacturing 00., Torrington, Conn., a corporation of Connecticut Application May '7, 1945, Serial No. 592,488

Claims. 1

This invention relates to improvements in blower wheel bracing, and more particularly to an improved arrangement of struts or braces for centrifugal blower wheels or similar rotors.

The invention has as a major objective, an improved construction of struts or brace elements such as to impart greater resistance to centrifugal blower wheels, against cocking stresses, and stresses incident to extreme or unusual torque conditions which might otherwise result in a relative angular displacement of different parts of the wheel.

More particularly expressed with reference to the present structural novelty, the present invention realizes objectively a novel arrangement of brace elements disposed internally of a centrifugal blower wheel, in such manner as not to interfere noticeably with the normal flow of air from the inlet through the blades of the wheel.

A still further object of the invention is obtained in a novel arrangement of strut elements for a centrifugal blower wheel, such that the struts or braces may be formed integrally with one of the plate or ring elements of the wheel, and requiring but a single assembly operation for securement of the free end of each strut as originally formed; further, objectively resulting in some saving in material as a result of formation of the struts integrally with a blanked out metal plate or ring of the wheel.

A further object of the invention is obtained in an improved wheel strut which is so disposed and utilized in a centrifugal blower wheel that it need not interfere in any way with assembly of the usual Wheel elements to the hub of the wheel, as for shaft assembly purposes, and at the same time serves markedly to strengthen the wheel against stresses imparted angularly to the wheel elements, as well as those imposed in a direction axially of the wheel.

The foregoing and numerous other objectives will become more apparent from the ensuing description, considered in connection with the accompanying drawing, in which:

Fig. 1 is an end elevation of centrifugal blower Wheel equipped with the improved bracing arrangement;

Fig. 2 is a sectional elevation of the wheel as viewed along an axial plane, particularly along line 2-2 of Fig. 1;

Fig. 3 is a plan view of a blank of metal or the like in and from which are formed, integrally, an end ring of the wheel and a plurality of the elements forming the wheel struts, and

Fig. 4 is a transverse section taken through one 2 of the strut or brace elements, particularly along line 4-4 of Fig. 1.

In order to coordinate the present description with the drawing, it may be noted for completeness that the wheel shown is of a type embodying a number of parallel blade elements, a requi site plurality of which are indicated at In. These blades occupy, as shown and as usual, the periphery of the wheel, and serve to displace the air from the chamber internally of the Wheel, whence it is displaced outwardly thereof into the usual volute chamber of a suitable housing. The wheel, as shown, is characterized by one closed end and one open end, the closed end being provided by a back plate H, which in assembly is opposite and parallel to an inlet ring [2. Tongues i3 and 14 formed as integral portions of the blades, extend into slots l5 of the inlet ring end It of the back plate, and the tongues may be secured as by suitable deformation or by welding (not shown).

For shaft mounting the wheel, a hub 26 is pro Vided, and is formed to include a shaft bore 25 and arranged for firm angular securement to the shaft, as by a set screw 22. Assembly of the hub 20 to back plate ll may be effected in any of a variety of Ways, for example, as by spinning over an extended portion 23 of the hub so that the latter is brought to overlie the metal margins about a central hub aperture 24 initially provided in the back plate II. This feature forms no part of the present inprovement, but is shown and described in Letters Patent 2,334,320, issued November 16, 1943, on an application of Addison W. Evans.

It is preferred, although not strictly essential to the operativeness of the present improvements, to form the back plate ll so as to provide an instruck portion in the form of a circular area 25. This serves somewhat to impart a greater planar rigidity to the back plate, and results in a shoulder 26 of circular form, which has a further ad vantage hereinafter better appearing.

The foregoing description, with but few exceptions, relates to features which have heretofore been practiced by applicants assignee, and in some cases by other manufacturers. Such description is introduced for completeness and as background material.

Proceeding now to describe the bracing or strut structure, constituting the principal feature of novelty of the present improvement, it will be noted from Fig. 3 that the inlet ring !2 consists of a modified annulus, a central opening 21 constituting the air inlet opening to the interior of the wheel, as is usual in wheels of this general type. It is accordingly formed as a planar, ringlike structure, as by stamping, say of sheet metal of suitable gage, or of other material possessing requiste strength. In the current example, the ring I2 is provided with a plurality, shown as three, internally extending chord-like strips 30. These are or may be initially fiat in form, and of even width throughout their length, except preferably being somewhat widened in the zones 3| where they join the material of ring l2, and, if desired, also at their free ends. The length of the portions 30, which as will now be obvious, result in the struts or braces of the wheel, will of course depend upon the depth or axial dimension of the wheel, and also somewhat upon the particular zones of anchorage desired for the inner or plate ends of the resulting braces. However, with wheels of moderate depth, and when employing three such brace-forming strips, each strip is of a length substantially to meet in the original blank, the base of the next adjacent strip, proceeding counterclockwise as in Fig. 3. The extensions or strips 30, in the original blank are, as will appear in the drawing, preferably continued from the inner circle of ring l2 in equiangular zones, being in Fig. 3 substantially 120 degrees apart. It will now have appeared obvious that in case the ring and strut blank is formed, as is preferred, by punching or stamping as a press formed unit, the end ring may, although not strictly necessary, be first assembled over the tongues l3 of the series of blades l8 and ssembly of the struts or braces thereafter completed. Assuming for the sake of convenience that the major elements of the wheel, including back plate and ring, are now completely assembled, the struts are now completed by bending or partially folding the strips in each of the several zones 32, so as to bring the strip inwardly of the wheel. The direction of folding or bending in each zone 32 is by preference such that the resulting strut 3D is not only brought depthwise into the wheel, but bears a distinctly acute-angular relation to a diametral plane containing the axis of the wheel. The depthwise trend of the braces or struts 30 will best appear from Fig. 2, while their angular deflection will best appear from Fig, 1.

Each of the strut forming strips is, by considerable preference, of an appreciably greater length than merely necessary to effect tangency of the inner brace ends with the back plate. There thus results at the otherwise free end of strip 30, sufficient material to constitute at the end thereof a securement tab 33, which is shown as somewhat wider than the body of the strip. These tabs necessarily lie at an appreciable angle to the axis of each brace strip, and are folded with respect thereto, each along the fold line 34.

Although the brace-forming elements are distinctly practical without imparting thereto any particular sectional shaping, it is preferred both for strengthening and in a certain measure to decrease their air resistance, to impart to each of the strips 39 a distinct curvature in the portion between fold lines 32 and 34, an example of which will best appear from the section of Fig. 4. When thus conformed, the braces are so curved and presented in the structure that the convex side of each thereof is presented toward the inlet of the wheel, hence toward the incoming air stream. In case the back plate is provided as shown with the instruck area and the resulting shoulder 26, it is a preference to locate the tabs 33 of the struts with their radially innermost margins adjacent. this shoulder. Assembly of the .4 tabs in these regions is preferably made as by spot welding.

The function of the wheel is, in a broad sense, not altered over conventional practice, by the present invention. There is however imparted to the wheel, as will now be apparent, a markedly greater rigidity against collapsing stresses, and against endwise upsetting pressures sometimes imparted in shipping or storage. Much more important, however, it will now have appeared that by virtue of the present bracing, cocking stresses which might otherwise tend to bring the plate l l and the ring [2 out of true register if not out of parallelism, are effectively opposed by the bracing. Of perhaps equal importance is the utility of the present structure in wheels which are subjected, in operation, to irregular torque impulses, for example in wheels of reasonable size powered by direct connection to single cylinder internal combustion engines or the like, or in other situations wherein torque application is characterized by undesirable peaks tending angularly to displace the plates or ring elements of the wheels. It is important to note that the presently described braces are designed to serve, as determined by varying wheel stresses, either as tension elements, or as compression struts. I am aware that it is old in the art, to provide integral spider arms or spokes, integral with a wheel rim or ring. As far as is known to this applicant, such structures are not, as is the present, structurally independent of the hub or other shaft engaging element. It may be noted further that wire spokes have been employed heretofore as blower wheel bracing elements, but of course serve solely as tension elements.

It will now have appeared that the invention serves fully to attain each of the objectives herein above specifically noted and others implied from the description of elements of assembly.

Although the invention has been described by making detailed reference to a single preferred embodiment, the detail of description is to be understood solely in an exemplary sense, and not as limiting the invention, numerous changes being possible within the scope of the claims hereunto appended.

I claim as my invention:

1. In a cylindrical blower wheel of open interior construction, a series of spaced, parallel displacement blades arranged to form a peripheral wheel body, an annulus at each end of the wheel body and assembled thereto, a hub assembled to one annulus for shaft-mounting the wheel, and a plurality of braces formed integrally with, and ex tending from equi-angular zones of the other annulus, each bracev being located interiorly of the wheel and s0 disposed that the longitudinal axis of the brace extends at an acute angle to an axial diametral plane of the wheel, the braces being assembled in the regions of their otherwise free ends, directly to the first said annulus.

2. In a centrifugal blower wheel of open interior construction, a series of parallel, spaced blades forming a peripheral wheel body, a plate secured to one end of the body, a ring secured to the opposite end of the body, a hub for shaftmounting the rotor, and assembled to the plate, a plurality of braces, each extended at an angle inwardly of the ring end of the wheel and each attached at one end to said ring, the plate being provided with projecting portions extended inwardly of the wheel, and providing a shouldered seat for the plate end of each brace, the plate end of each brace being secured to the plate in the region of the shouldered seat therefor,

3. In a centrifugal blower wheel of sheet metal construction, a circular back plate provided with axial opening, a hub for shaft-mounting the wheel and extended through and secured to the material about the back plate opening, an inlet V ring, a plurality of sheet metal struts formed as inwardly extended tongues integrally with the end ring, the back plate having a substantially circular instruck portion formed therein, so as to present a shouldered margin internally of the wheel, and each of said struts being provided with an angulatc end tabbent at an angle thereto, the tab being superposed on and secured to the back plate and engaging a portion of the said shouldered margin.

4. As an article of manufacture, for use as a part and in the ssembly of a centrifugal blower wheel or the like, a sheet metal blank of substantially circular outline, and in the form of a modified annulus, the blank including a substantially triangular arrangement of three struts formed integrally with and extending across the area within the annulus, each said strut bearing a substantially chordwise relation to the inner circle of the annulus.

5. In a centrifugal blower wheel of sheet metal construction, a plurality of spaced parallel displacement blades forming the periphery of the wheel, a back plate assembled to the ends of the blades at one end of the wheel, an inlet ring similarly assembled to the opposite ends of the blades, a hub for shaft-mounting the wheel, the back plate having a central hub opening, a hub being secured to the metal of the plate about said opening, three wheel struts formed integrally with the end ring and each extended inwardly of the ring proper, but folded in the zone of its juncture with the ring so as to extend both toward the back plate and at a distinct angle to an axial diametral plane of the wheel, the back late being formed to provide an instruck projection internally of the wheel and presenting a shoulder for engagement by each of the braces at a substantial distance outwardly of the wheel hub, each brace being characterized by a flattened end portion most remote from the end ring and being assembled to the back plate by disposition of said flattened portions in parallel adjacence to the plate and in edgewise abutting relation to said shouldered portions, each brace being channelled over the greater part of its length between its end securement zones for purposes of strengthening, and being disposed in the wheel so as to present a con vex surface toward the air stream proceeding inwardly through the ring, thence outwardly across the blades, the braces being relativel somewhat convergent from the inlet ring toward the back plate, and each brace being secured to the back plate in a zone angularly displaced in respect to its zone of connection to the inlet ring, the braces further being formed of sheet or strip metal of a character and gauge such that they are adapted to serve selectively as compression and as tension elements.

CHARLES I. PLACE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,362,868 Upson Nov. 14, 1944 1,863,043 Johnson June 14, 1932 

